This invention relates, in general, to an oil separating system for separating engine oil mist from blowby gas to be recirculated to an intake system of an internal combustion engine, and more particularly to an oil separator disposed in a crankcase in connection with a jackshaft for operating engine accessories.
It is well known that a modern internal combustion engine is equipped with a so-called blowby gas recirculation system or positive crankcase ventilation system by which blowby gas having blown into a crankcase, through between a piston and a cylinder wall, is recirculated back to a combustion chamber of the engine through an intake manifold so that the blowby gas is burned in the combustion chamber to prevent air pollution. As apparent, the crankcase is filled with engine oil mist and accordingly the oil mist is also sucked through an intake passage to the combustion chamber along with the blowby gas. Accordingly, the inner wall surface of the intake passage and the inside of the combustion chamber are soiled with the sucked oil mist, causing increase in engine oil consumption.
In this regard, the oil mist is in general separated from the blowby gas by using the difference in specific gravity between the oil mist and the blowby gas by the following measures: a blowby gas outlet through which blowby gas is taken out from a crankcase is located at a section which is not likely to suck splashed engine oil in the crankcase. Additionally, a relatively large volume of oil separating chamber of an oil separator is disposed at such a section, by which the flow rate of the gas in the oil separating chamber is lowered to prolong the staying time of the gas. Further, a metal mesh or obstruction plates are disposed at a passage communicating the oil separating chamber with the inside of the crankcase.
However, such an oil separator has encountered the following problems: the location of the oil separator is unavoidably decided depending upon the direction of the rotation of the crankshaft. Accordingly, the freedom in selecting the location of the oil separator is restricted by this reason. Additionally, in case where the above-mentioned oil separating chamber is formed integrally with an engine body, the oil separator which is restricted in selecting its location is disadvantageous from the standpoints of obtaining suitable spaces in an engine room, decreasing engine weight, and facilitating production or casting of the engine. In other words, depending upon engine types, it may become necessary to locate the oil separating chamber of the oil separator at the opposite side to an intake manifold relative to the axis of the engine body. This requires an extremely long suction pipe through which the blowby gas is recirculated to the intake manifold, raising the problems to increase cost and weight and deteriorating appearance of the engine. Additionally, if a large volume of separating chamber is formed at the same side as the intake manifold relative to the axis of the engine body, there rises an apprehension to make difficult the installation of an exhaust gas treating device such as a catalytic converter or a thermal reactor.